Method of mounting an integrated circuit on a printed circuit board

Abstract

A method of mounting an integrated circuit having a plurality of leads on a printed circuit board (PCB), by: removing foreign substances on the PCB; spreading a flux on lead patterns formed on the PCB; aligning the leads of the integrated circuit on the lead patterns on the PCB on which the flux is spread; soldering the leads and lead patterns by covering the part of a semiconductor chip of the aligned integrated circuit using a holding block and radiating an optical beam onto the whole surface thereof; and cooling the holding block and PCB which has been soldered, which prevents shorts and a poor contact generated by an earlier method. As the quality of soldering is enhanced and the lead is not pressured when soldering, the confidence of the integrated circuit after mounting is also enhanced. Moreover, by soldering all of the leads at one time, the operational time can be reduced.

What is claimed is: 
     
       1. A method of mounting an integrated circuit having a plurality of leads on a printed circuit board (PCB), comprising the steps of: removing foreign substances on said PCB;   spreading a flux on lead patterns formed on said PCB;   spreading a conductive bond over a part of said PCB where the semiconductor chip of said integrated circuit is positioned, said conductive bond being spread over the area corresponding to 60% of the area of said semiconductor chip;   aligning the leads of said integrated circuit on the lead patterns on said PCB on which the flux is spread;   soldering said leads and lead patterns by covering the part of a semiconductor chip of said aligned integrated circuit using a holding block and radiating an optical beam onto the whole surface thereof; and   cooling said holding block and said PCB which has been soldered.   
     
     
       2. The method of claim 1, said conductive bond being simultaneously spread over the surface of said PCB and over a back side of said PCB by a via hole formed through said PCB. 
     
     
       3. The method of claim 2, a heat sink being attached using said conductive bond spread over the back side of said printed circuit board. 
     
     
       4. The method of claim 1, said flux being spread using a nozzle. 
     
     
       5. The method of claim 1, said flux being spread using a stamp in which said lead patterns are carved. 
     
     
       6. The method of claim 5, said PCB being fixed by a magnet fixing jig, before aligning said integrated circuit thereon. 
     
     
       7. The method of claim 6, said PCB being fixed by a combination of a magnetic substance attached to said holding block and said magnet fixing jig. 
     
     
       8. The method of claim 5, a recognition mark being formed on said PCB to align said integrated circuit on said PCB. 
     
     
       9. The method of claim 5, a xenon Xe lamp being used as a source of said optical beam. 
     
     
       10. The method of claim 5, the leads of said integrated circuit being aligned on the lead patterns on said PCB after adhering said integrated circuit through said holding block. 
     
     
       11. The method of claim 1, said printed circuit board being fixed by a magnet fixing jig, before aligning said integrated circuit thereon. 
     
     
       12. The method of claim 11, said printed circuit board being fixed by a combination of a magnetic substance attached to said holding block and said magnet fixing jig. 
     
     
       13. The method of claim 1, a recognition mark being formed on said printed circuit board to align said integrated circuit on said printed circuit board. 
     
     
       14. The method of claim 1, a xenon Xe lamp being used as a source of said optical beam. 
     
     
       15. The method of claim 1, the leads of said integrated circuit being aligned on the lead patterns on said printed circuit board after adhering said integrated circuit through said holding block. 
     
     
       16. A method of mounting an integrated circuit having a plurality of leads on a printed circuit board (PCB), comprising the steps of: removing foreign substances on said PCB;   spreading a flux on lead patterns formed on said PCB;   aligning the leads of said integrated circuit on the lead patterns on said PCB on which the flux is spread;   spreading a conductive bond over a part of said PCB where the semiconductor chip of said integrated circuit is positioned, said conductive bond being spread over the area corresponding to 60% of the area of said semiconductor chip;   simultaneously soldering said leads by covering the part of a semiconductor chip of said aligned integrated circuit using a holding block portions of which that correspond to said leads having been cut away so that only a semiconductor chip portion of said integrated circuit can be covered, and radiating an optical beam simultaneously onto the whole surface thereof excluding said semiconductor chip portions; and   cooling said holding block and said PCB which has been soldered.   
     
     
       17. A soldering apparatus for soldering an integrated circuit having a plurality of leads on a printed circuit board (PCB), comprising: a table for fixing a PCB having at least one aligned integrated circuit, and having a portion thereof opened correspondingly to said integrated circuit;   a spreader for spreading a conductive bond over a part of said PCB where the semiconductor chip of said integrated circuit is positioned, said conductive bond being spread over the area corresponding to 60% of the area of said semiconductor chip;   a holding block having a portion thereof that corresponds to said leads of said integrated circuit having been cut away so that only a semiconductor chip portion of said integrated circuit can be covered; and   a means for radiating an optical beam onto the whole surface of said PCB when said holding block covers said semiconductor chip portion of said integrated circuit.   
     
     
       18. The soldering apparatus according to claim 17, said holding block having supporting portions having a selected height at the four edges thereof, magnetic substances are combined to respective ends of said supporting portions, and magnets are buried in portions of said table that correspond to said supporting portions, said magnetic substances and magnets being coupled magnetically. 
     
     
       19. The soldering apparatus according to claim 18, said holding block having a plurality of penetrating holes at a center thereof. 
     
     
       20. The soldering apparatus according to claim 19, recognition marks being formed on opposite edges of said PCB that oppose to each other.